1 Introduction

A common drawback with constant on-time (COT) control topologies is the switching frequency variation and inability to synchronize to an external clock. TI’s fixed-frequency direct control with seamless transition into power save mode (fixed-frequency DCS-Control) topology builds on the popular COT DCS-Control topology with its fast transient response, and adds an oscillator to achieve fixed-frequency operation with optional clock synchronization. This combination enables applications that require both a fast transient response and have specific noise or frequency requirements.

Other features such as differential remote sensing, external control-loop compensation and stackability support the demanding transient requirements of higher-current processors found in noise-sensitive applications, including automotive infotainment and advanced driver assistance systems (ADAS), communications equipment optical modules, industrial test and measurement, medical, and aerospace and defense. This article provides an overview of the fixed-frequency DCS-Control topology, discussing its excellent transient response, constant and synchronize-able switching frequency, lower-ripple power-save mode, and stackability for higher currents.